MAKE AN UNDERWATER VOLCANO  more experiments

Video:  watch Miss Mary do this experiment on Let's Talk Live, ABC News Channel 8.  This is an experiment from our Blast & Bubble Birthday Party!

Materials:

2 cups vegetable oil

1/2 c. vinegar

food coloring (optional)

1 T. baking soda

water

tall clear class or vase

rubbing alcohol (optional)

Directions: 

Pour the oil into the tall clear container.  Add food coloring to the vinegar so the layer will be more visible.  Pour the vinegar into the oil and watch as it settles to the bottom.  If you have rubbing alcohol, add food coloring to this and gently pour it  into the oil. It will rise to the top giving you three layers!  In a separate container, mix just enough water into your baking soda to form a thick paste.  Now drop about 1/4 tsp. of the paste into your container. Watch as it sinks to the bottom then causes big blobby bubbles to rise through the oil.  You can keep the reaction going by adding more baking soda and more vinegar as necessary.

Science: 

Liquids have different densities.  Less dense liquids will float on top of more dense liquids.  For example, both water and vinegar are more dense than oil.  That's why when you make salad dressing the oil floats on top.  To mix them together, you have to stir or shake them with enough force to form an emulsion.

Vinegar is an acid; baking soda is a base.  When combined in a solution, they cause a chemical reaction that gives off carbon dioxide gas (the same gas humans exhale). 

When you drop the baking soda paste through the oil, it becomes coated with the oil as it sinks through to the vinegar on the bottom.  As the baking soda emerges from the oil, it combines with the vinegar to cause an acid base reaction.  The carbon dioxide gas bubbles pass through the oil layer and are trapped in big blobby bubbles until they float to the top and pop!  This looks like an underwater volcano

Underwater volcanoes, of course, have nothing to do with acid/base reactions.  Volcanoes are the same whether they are above or below ground -- they occur when molten lava erupts through openings in the Earth's crust.

Vocabulary:

• Acid:  a compound usually having a sour taste and capable of neutralizing alkalis and reddening blue litmus paper, containing hydrogen that can be replaced by a metal or an electropositive group to form a salt, or containing an atom that can accept a pair of electrons from a base. Acids are proton donors that yield hydronium ions in water solution, or electron-pair acceptors that combine with electron-pair donors or bases.  (Dictionary.com)

• Base:  a) a compound that reacts with an acid to form a salt, as ammonia, calcium hydroxide, or certain nitrogen-containing organic compounds. b) the hydroxide of a metal or of an electropositive element or group. c) a group or molecule that takes up or accepts protons. d) a molecule or ion containing an atom with a free pair of electrons that can be donated to an acid; an electron-pair donor. e) any of the purine and pyrimidine compounds found in nucleic acids: the purines adenine and guanine and the pyrimidines cytosine, thymine, and uracil. (Dictionary.com)

• Solution:  a homogeneous, molecular mixture of two or more substances. (Dictionary.com)

• Reaction:  a chemical change.  (Dictionary.com)